VvMYBPA2 Regulated the Accumulation of Flavan-3-ols though Forming a Trimeric Complex in ‘Zaoheibao’ Grape

Abstract

Flavan-3-ols are monomers of Proanthocyanidins (PAs), which are important polyphenolic compounds in grapes. Previous studies had shown that VvMYBPA2 was closely related to grape flavan-3-ol monomers biosynthesis, but its regulatory network is still unclear. Here, we found that the contents of (+)-catechin and (−)-epicatechin, the enzyme activities of anthocyanidin reductase (ANR) and leucoanthocyanidin reductase (LAR) and the expression of VvANR and VvLAR1 were increased in the VvMYBPA2 overexpression grape leaves compared to the control. It was proved that VvMYBPA2 protein interacted with VvWDR1 and VvWDR1 protein interacted with VvMYC2 by yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC). The promoters of VvANR and VvLAR1 were bound by VvMYBPA2 using yeast one-hybrid (Y1H) assay. These results suggested that VvMYBPA2 could form a trimeric complex with VvWDR1 and VvMYC2 and jointly regulated the expression of flavan-3-ol monomers related genes VvANR and VvLAR1, thereby affecting the enzyme activities of ANR and LAR and ultimately regulating the contents of flavan-3-ols.

UV-C Promotes the Accumulation of Flavane-3-ols in Juvenile Fruit of Grape through Positive Regulating VvMYBPA1

“…The pMD-VvMYBPA1 vector and pCAMBIA1300 empty vector conducted a double enzyme digestion using Hind III and Sal I, then connected two enzyme cleavage products using T4 DNA ligase (Supplementary Table S1), constructed 35S::VvMYBPA1 vector, and converted it into competent cells of Agrobacterium tumefaciens GV3101. Green grape leaves were infected with Agrobacterium tumefaciens containing empty and 35S::VvMYBPA1 vectors for 10 min, respectively [24]. After infection, put them into a light incubator for culture.…”

“…Previous studies had showed that UV-C irradiation positively regulated VvLAR enzyme activity to promote the accumulation of total flavane-3-ols in early grape fruits [23], but its molecular regulation mechanism was still unclear. At present, studies on the regulation of grape PAs accumulation by a MBW trimer complex have been reported [24,25]. In this study, the different period grape fruits after UV-C irradiation treatment were used as experimental materials to explore the molecule mechanism of flavane-3-ol monomers in grapes.…”